Cadillac Seville / Cadillac Eldorado Forum Discussion, Are the 4.9L's good over 140,000 miles in Past Cadillac Vehicle Discussion; No. We consistently found component life-cycle failures (including engines/trans) of 100K miles or more....

The thick white smoke was really oil not steam, i could smell it and taste it , it was so thick. that was around 7pm one evening

Funny thing was the very next morning, 9am-ish, there was not smoke but the metallic tapping noise was very evident.

when i drove it home, there might have been a slight loss of power, but i wasnt pushing it.

i bought the car used, cause it was in such nice condition, and cause the carfax showed that it only had 1 owner previous. and more importantly an owner that religiously took it in for the yearly smog inspections(routine inspections might imply routine maintenance too) in Arizona(so very little chance of rust).

i hadnt looked at the coolant, but i will. I'm sure it's the green stuff. I had the pink stuff in my 1996 since new and it still rusted out the waterpump within 3 years. Happened just after my warranty ran out, just about the same time my AC compressor went out too.

Head gasket sounds plausible, but what could be causing the tapping noise?

Originally posted by Katshot Junkyard motor.
God I hope Jason and Brett don't read this, it might shake their faith in the almighty Northstar

LOL....i dont have near enough Cadillac engine knowledge to argue with you or Jason on the subject, also never claimed to.
My experience with the northstar has consisted of 31k miles on an 01 Seville. Very trouble free miles, but hardly makes me an expert.

Originally posted by Katshot No. We consistently found component life-cycle failures (including engines/trans) of 100K miles or more.

"Life cycle" failures and manufacturing failures seem to be completely different subjects. A life cycle failure being wear due to age/fatigue and manufacturing failures being due to improper assembly. Example, a life cycle failure of a water pump bearing after 110k miles. Example, a manufacturing error where the head bolts were too long and engine blew coolant after 2000 miles out the door.

You seem to be glumping life-cycle failures in together with a manufacturing defect(s). Is there a difference? Seriously...I lost you on this one. Am I mixing up my terms?

They can overlap actually. I could've been more careful with the terms though.

Over the years the two tend to blend together from time to time.
Example: Your waterpump life-cycle, what caused the bearing failure? was it properly installed? Maybe not. Does that same bearing deliver a substantially longer or shorter service life in another application? All too often, I've found that "life-cycle" (being a very subjective term) is greatly determined by component failures. The waterpump life-cycle of 110K miles was really determined by the component failure of a bearing that may have failed due to a manufacturing problem. That kind of thing happens all the time.
What I was getting at was that we had routinely found major components like engines and transmissions (just to name a couple) had exibited a rather specific life-cycle due to a component failure. Suppose just for arguement sake that 80% of the Northstar engines in my '98 Devilles exibited a blown head gasket by 120K miles. Could I not assume to give those engines a realistic "life-cycle" of 120K miles? Of course.

Right, I agree with all of the above. But to follow your head gasket example, I was trying to separate manufacturing/assembly error with component fatigue.

If 100% of your vehicles made it to 120k miles w/ no problems, then all of a sudden, 80% of them failed a head gasket, I would assume that they were all assembled correctly, but the "lifetime" of the head gaskets happened to be about 120k miles.

Conversely, I would expect assembly problems to show up much earlier in the component life. Such as the case with the reported head bolt holes that were a smidge too short I think. I would expect the clamping load of the head bolts to be MUCH less than designed, and I would rightly expect the engine to fail within a few thousand miles, if it made it out of the factory at all.

I'd consider my first example a "life-cycle" failure because the actual component was wore to its designed life cycle (in this case, 120k miles on a head gasket). I'd consider the second example an "assembly error" because the engine had not been properly assembled and premature failure resulted because of it.

That's how I assumed the terms were defined. And having said all that, I think maintenance does play a role in the life-cycle failures. The head gasket is a good example of that. Say the gaskets are expected to last 75k miles if you run green coolant and perform no maintenance, and are expected to last 150k miles if you run green coolant, and change it every 2 years. In this situation, I'd consider failure of a head gasket in both cases life-cycle failures, but the head gasket that failed prematurely was the fault of the owner (no maintenance) and would have lasted up to twice as long with proper maintenance. Does that make sense?

Originally posted by Katshot Example: Your waterpump life-cycle, what caused the bearing failure? was it properly installed? Maybe not. Does that same bearing deliver a substantially longer or shorter service life in another application? All too often, I've found that "life-cycle" (being a very subjective term) is greatly determined by component failures. The waterpump life-cycle of 110K miles was really determined by the component failure of a bearing that may have failed due to a manufacturing problem. That kind of thing happens all the time.

I see what you're saying here. Sure, it may have failed due to a manufacturing problem. It also may have failed due to old age. I was impressed to see 110k miles from a water pump; I'm used to seeing them go after 60-70k miles. I assumed it just failed due to old age/fatigue.

It may also not have failed at all. I trusted the shop's recommendation to change the pump, so I changed it. The leak was still there for a while. It appears to have been coming from the water pump COVER gasket. Doh! Since the engine has been dosed with a new shot of the cooling system tabs (when I put the new coolant in), the leak has slowed and has stopped now I think.

BTW, what's the deal with the pumps rusting? I've heard about this from a few people. Even after 110k miles, mine slipped right out. I think my engine's a freak.

I would usually define "Life-Cycle" as a component's average service life as determined by statistical analysis of component failures.

If you have a component failure rate of near 100% at "X" miles, that component's "Life-Cycle" would be considered to be "X" mile, regardless of WHY the component failed. If you determine that the component failed due to some sort of sub-assembly or part failure, then you would research the reason for the sub-assembly/part failure. Upgrading the spec for that failed subassembly/part would then increase the "Life-Cycle" of the overall component. RIGHT?
Now add to that scenario that just maybe through your research, the sub-assembly/part failure was due at least in part, to an improper torque spec. or some other "manufacturing" issue. It still doesn't change the fact that the "Life-Cycle" of the overall component is "X".
Hell, I'm getting a headache here

Anyway,
The facts are that mechanical components (unlike electrical components) do not necessarily fail early on when there is a manufacturing fault. It can be at anytime. That's why there are so many "special" warranty extensions from the OEMs. Quite often the component failures don't happen until well beyond warranty coverage. Matter of fact, I just recently heard about a number of '00 and '01 Northstars that developed block cracks in a "specific" location. These engines ALL had in excess of 150K miles and it is generally believed that the old head bolt issues are revisiting these engines once again. There is some thought that there MAY have been some fatigue in the surrounding casting due to the improper head bolt drillings.

Originally posted by Katshot If you have a component failure rate of near 100% at "X" miles, that component's "Life-Cycle" would be considered to be "X" mile, regardless of WHY the component failed. If you determine that the component failed due to some sort of sub-assembly or part failure, then you would research the reason for the sub-assembly/part failure. Upgrading the spec for that failed subassembly/part would then increase the "Life-Cycle" of the overall component. RIGHT?
Now add to that scenario that just maybe through your research, the sub-assembly/part failure was due at least in part, to an improper torque spec. or some other "manufacturing" issue. It still doesn't change the fact that the "Life-Cycle" of the overall component is "X".

(okay, now I'm going to get a headache...but I LOVE these discussions!)

I agree with you except for the last part. I guess how I define "life-cycle" and how the industry defines it is a bit different... I think, that if a manufacturing error or maintenance neglect produced a premature failure, that component would not have experienced a "life-cycle" failure, because error was mass-produced into the engine (like the bolt holes) and premature failure resulted (premature, relative to the component's life in a "correctly" assembled engine).

This is why I brought in the maintenance issues to the original head gasket comment. If the gaskets failed due to corrosion, which was traced back to improper cooling system maintenance, I don't consider that the "fault" of the engine, and I wouldn't consider it to be a "life-cycle" failure in this case, because if proper maintenance was realized, the gaskets may not have failed.

I guess I consider a component's "life-cycle" to be in general, applicable to ALL the components as a batch (meaning, the designed reliability of all the Northstar head gaskets ever produced), regardless of the environment in which they're implemented. But I can see it the other way too. Example, a batch of 1000 engines had "incorrect" bolt holes and their head gaskets all failed at 50k miles. In this case, the industry considers the "life-cycle" for THESE sets of head gaskets to be 50k miles. But in a batch of 1000 engines that were correctly machined, the "life-cycle" for THOSE gaskets might be three times that.

Yeah, you're getting it. Although I think the "Life-Cycle" is actually a by-product of all the above. Whatever affects the component life, has the ability to affect the "Life-Cycle". "Life-Cycle" is just basically a fancy way of saying the useful life, or life expectancy.
My head is spinning dude

In a few very select situations I'd like to be able to turn it off to roast the tires just to show off, but in general, it kinda helps me along.

Example, we were going to the mall last Saturday and had to merge into traffic with very little merge lane available. The road was wet and the traffic thick. Well, my style is to press it and go. We were going about 35, and it downshifted into 1st and broke both fronts loose and shifted a little towards the left, but not too much. I just kept it on the floor and the T/C brought it back inline and we zoomed off...then had to slam on the brakes cuz we ended up going about 20 mph faster than everyone else.

I can disable it, but it forces a 2nd gear start, supposedly to prevent differential scoring and shock to the driveline if the tires were to spin wildly.